The 5-alkyl-1,3,4-oxadiazol-2-thiomethylthiocyanate and 5-alkyl-1,3,4-thiadiazol-2-thiomethylthiocyanates compounds are known and taught by Staller et al. in German Patent Offenlegungsschrift 25 41 388. These compounds are taught to be useful as plant fungicides.